1. Field of the Invention
The present invention relates generally to power over Ethernet (PoE) and, more particularly, to a PoE power sourcing equipment architecture for variable maximum power delivery.
2. Introduction
In a PoE application such as that described in the IEEE 802.3af and 802.3at specifications, a power sourcing equipment (PSE) delivers power to a powered device (PD) over Ethernet cabling. Various types of PDs exist, including voice over IP (VoIP) phones, wireless LAN access points, Bluetooth access points, network cameras, computing devices, etc.
In accordance with IEEE 802.3af, a PSE can deliver up to 15.4 W of power to a single PD over two wire pairs. In accordance with IEEE 802.at, on the other hand, a PSE may be able to deliver up to 30 W of power to a single PD over two wire pairs. Other proprietary solutions can potentially deliver even higher levels of power to a PD.
In accommodating the ever-increasing range of potential power delivery levels it is important that the field effect transistor (FET) design of the PSE have sufficient flexibility. What is needed therefore is a PoE PSE architecture for variable maximum power delivery.